The present invention generally relates to a safety control mechanism for a reciprocating press brake assembly of the type used to bend sheet metal or the like. In particular, the present invention is directed to a safety control mechanism requiring both of an operator's hands to actuate movement of a ram member toward a workpiece. After the ram comes within a predetermined distance of the workpiece, movement of the ram is automatically stopped, with a foot pedal being actuable for controlling further movement of the ram, thereby freeing the operator to grasp and position the workpiece during the actual work operation without fear of his hands being caught between the ram and workpiece.
While press brake assemblies for bending sheet metal are well known, safety control devices for such assemblies have generally proven unsatisfactory with regard to allowing an operator to control the placement of the workpiece during the work operation. It would be most desirable for an operator to be able to hold and place the workpiece as the ram assembly makes actual contact therewith, thereby allowing the operator to position the workpiece against guide stops and further allowing the operator to feel and recognize possible slippage of the workpiece during the bending operation.
The Occupational Safety and Health Administration (OSHA) requires than an operator's fingers be at least 12 inches from a ram and associated bending die as they approach one another, but the fingers can be placed much closer to the ram after the gap is reduced to 1/4 inch or less.
An assembly which is typical of the prior art and which meets the OSHA requirements is disclosed in U.S. Pat. No. 2,199,501, issued May 7, 1940 to MacBlane, which suggests two hand controls and a foot control, wherein both hand controls must always be depressed to actuate movement of the ram assembly. This safety control mechanism does not allow for the handling of the workpiece and is difficult to precisely position the workpiece with respect to the ram.
As will be discussed in detail hereafter, applicant's new and useful invention solves the problems confronting the prior art, by providing a safety control mechanism which positively assures an operator's safety, while still allowing hand contact with the workpiece during the actual work operation.